Resurfacing stormwater at the new Sherbourne Common

Last Friday, Waterfront Toronto unveiled Sherbourne Common, the latest in a string of connected parks that it has been developing along the city's central and eastern harbour. While the grand opening took place in the nearly completed part of the park south of Queen's Quay, work continues on the north side's sweeping water sculptures and raised biofiltration beds.

Sherbourne Common occupies both sides of Queens Quay East at Sherbourne Street, and is just the first phase of what will be an ambitious set of development projects accompanied by an innovative stormwater system on the waterfront lands between Sherbourne and Cherry Street. Similar to other recent Waterfront Toronto parks like Sugar Beach and the Wave Decks along the central waterfront, the park is intended to be a public space, a link between the city and the lake, and a catalyst for private investment in the surrounding lands.

Sherbourne Common contains an extensive network of surface water features that will ultimately be fed stormwater that has fallen in the planned East Bayfront neighbourhood. The park is part of a larger planned facility that will send stormwater through a several-stage treatment process, including sedimentation, oxygenation, passive and active UV filtration, and passage through biofiltration beds, before entering the lake. These facilities, integrated and partially exposed in the Common and in the planned Bayfront Promenade and Parliament Street Wave Deck, represent an innovative and forward-thinking approach to building 'hard' stormwater infrastructure, but a lot of work remains to be done to ensure this facility fulfills its potential.

Bringing stormwater up from the darkness

A series of artificial water features have been installed in the park. North of Queens Quay, tall, swept sculptures designed by Jill Anholt drop water from a height of nearly 9 metres into a chain of raised biofiltration beds. From here, the water is dropped beneath Queens Quay Boulevard to sump chambers on the south side, where it is pumped back to ground level, through additional raised beds and then down into a channel that runs down the east side of the south park and ultimately to the lake.

Ultimately, the water that feeds the park's water features will be drawn from the East Bayfront's stormwater management facility (SWMF), which is intended to be built out over the next few years. For the grand opening, the park's southern water features were operating on a closed water loop, but soon that loop will be replaced with water drawn from Lake Ontario, which will run through Sherbourne Common's UV filtration system before being sent to the surface. Once the sedimentation tanks of the East Bayfront Promenade have been installed, stormwater can begin to feed the park's fountains and channel, although conceivably lake water will continue to be used to maintain flow during dry periods (the sedimentation tanks are intended to sit in equilibrium with the prevailing lake level).

"No one can really tell where the infrastructure ends and the landscape of the park begins," says Peter Heyblom of The Planning Partnership, a local urban design and landscape architecture firm that partnered with Vancouver's internationally-recognized Phillips Farevaag Smallenberg firm and The Municipal Infrastructure Group (TMIG) on the project. The characterization is a good one: set aside the clean concrete lines of the park infrastructure, and the sumps beneath it could be imagined as natural grottos, while the future sedimentation tanks beneath the promenade will integrate almost seamlessly with the lake.

The park also contains a splash pad / skating rink that is fed conventionally from the municipal drinking water system and that drains into the sanitary sewer system. The intention was originally to send water drained from the splash pad into the park's treatment system, but health and environmental regulations appear to have presented an obstacle.

The park's landscape design is impressive. In particular, the Common succeeds in combining useable green space with its concept features in a way that feels neither tacky nor cluttered. Unlike high-concept, furniture-oriented parks like Sugar Beach to the west, the south section of Sherbourne Common feels very open and unprescribed. It is easy to feel confident that the park will succeed in being an integral part of a neighbourhood that still mostly exists only in planning sketches and marketing campaigns — this is not a tourist park, but neither is it a vacant green space, and the designers (along with the public authorities who chose to set aside this much development land for the park) should be congratulated for threading that needle as skillfully as they have.

Jennifer Nagai of Phillips Farevaag Smallenberg describes the park's design as a narrative about water in the city. "People want that experience," says Nagai of the opportunities the park provides to see and connect with the path of runoff from the city into Lake Ontario. "We were trying to figure out how to bring the infrastructure into service of that narrative."

Indeed, the park's key advance is to make visible, at least in a figurative sense, a connection between climate, land and water that is integral to the history and viability of cities, and to celebrate a hydrologic cycle that the last century and a half of stormwater policy has done its best to bury and obfuscate from the public's experience of urban living. We have spent a lot of money channelling water down into dark holes, never to be seen again; Sherbourne Common and the eventual East Bayfront Stormwater Management Facility at the very least bring it back up for us to see. Says Mike Elliot of TMIG, which is responsible for the engineering of the stormwater components in the park and throughout the East Bayfront, "the precedent has been set here, and people will see this project as the catalyst."

Lingering concerns

Sherbourne Common represents an exciting development in how we approach stormwater treatment and park design. That said, the park and treatment facility still depend on a variety of heavy infrastructure. In the new development, local storm sewers, and the planned Promenade and Parliament St. tanks, continue to spirit away and sequester the district's rainfall, only returning it to the park surface through the action of electric pumps and high-tech treatment equipment. City and provincial regulations governing water quality and sanitation haven't helped matters, constraining the possibilities for visible surface treatment and conveyance of stormwater.

As I've noted, the ultimate role of the park's water infrastructure as a part of a broader stormwater management facility awaits progress on the private development projects that surround the park and construction of the sedimentation tanks along the East Bayfront Promenade and at the Parliament slip that will feed clarified stormwater into Sherbourne Common's filtration system. The completion of the promenade, which will apparently allow the park to begin processing stormwater, is likely two or three years away. The ultimate success of the park as an integrated stormwater management facility and public space is still a work in progress.

Another challenge is what will be done with the contaminated silts that will have to be periodically removed from the Promenade and Parliament tanks. Right now they are likely to be sent to landfill, a blemish on the park and neighbourhood's promise of clean, LEED-certified urban living. The problem with this hard, technological, end-of-pipe approach is that we remain dependent on the pace of technological advancement and on what the development does not attempt to influence: the land-use, road-use and road-maintenance activities that dictate what kinds of contaminants are entering our stormwater stream in the first place. To be fair, the East Bayfront neighbourhood is to include in its catch-basins source controls intended to separate oil and grit from road runoff, but it seems this won't be sufficient to produce clean sediment in the tanks and again, this is a hard, invisible technology that accepts those input contaminants as a given.

Stormwater revealed, watershed forgotten?

While Sherbourne Common is an important development, a beautifully designed space, and an interesting evolution in the design and evolution of our stormwater infrastructure, the broader desire to restore continuity and clarity to our urban watersheds remains unfulfilled. In the 1990s, Brown+Storey Architects proposed a demonstration project for the west-end Garrison Creek watershed that would have built a series of surface rainwater ponds, fed by local storm sewers and surface runoff, in Christie Pits, Bickford Park, and the Montrose Schoolyard. While this plan was not realized, it had a great and lasting influence on the ways that many in Toronto have thought about watersheds and have sought to change the way that we approach them as a city.

At first glance, Sherbourne Common would seem to be a remarkable implementation of Brown and Storey's vision in another Toronto (sub-)watershed. However, the Common strays from that vision.

The park and surrounding development's position on modern fill land, and the particular geography of Toronto's network of interceptor sewers east of downtown, mean that the immediate area around Lower Sherbourne Street is quite isolated from its surrounding watersheds. However, the sewershed that passes through the East Bayfront neighbourhood's west side stretches as far north as Allan Gardens at Jarvis and Carlton Street, while the east side's sewage overflows originate near the intersection of Dundas and Parliament. These north-south combined and overflow sewers are reminders of the two creeks that once flowed across the old lakeshore (roughly where Front Street is) and into the lake at either end of the East Bayfront neighbourhood: the small Cathedral Creek just east of Jarvis and Front, and the much greater Taddle Creek which came all the way from the Annex and University to flow out into the lake near Parliament and Mill Street.

During significant rainfall, combined sewage overflows from Moss Park and Cabbagetown enter the harbour through a string of overflow pipes all around the Sherbourne Common. There is no connection between these sewers and the stormwater system being built for the East Bayfront development. Apart from providing a separate system of storm sewers that won't tax the area's overflow sewers (which sit at lake level and thus have fairly limited capacity to convey wastewater), the East Bayfront SWMF and Sherbourne Park's integrated water features have little to say or contribute to the broader watershed on whose invisible "mouth" the park is now situated.

The water passing through the planned stormwater management facility at/around Sherbourne Common is abstracted by the East Bayfront's self-contained storm sewer system — it is quarantined from the topological and historical watersheds that surround the new neighbourhood. By developing the system in this way (and leaving the question of the CSOs to a separate planning and EA process that is well on its way towards presenting Toronto with another buried storage system 3-4 times the length of the existing Western Beaches Storage Tunnel), Waterfront Toronto and the City have neglected an opportunity to forge connections between East Bayfront and the established (and indeed, historic) neighbourhoods to the north.

What Brown and Storey proposed with their Garrison Creek project was that stormwater systems "enlist the resources of the community landscape — neighbourhood, open space, individual and collective — to treat rainwater as a renewable, reusable resource instead of a disposable waste". 1 In many practical ways, Sherbourne Common and the East Bayfront SWMF get things right, reusing stormwater and allowing it to reenter the landscape and imagination of the new community that Waterfront Toronto is building in concert with private developers. However, this development remains a bubble of near-perfect, high-tech, capital-intensive stormwater management that neglects to contribute in a meaningful way to the watershed it shares with older neighbourhoods upstream.

None of this is a criticism of the design team, who have clearly produced an exceptional public space and integrated it in exciting ways with an infrastructure and waste stream that we usually don't get to interact with. If anything, it's a problem with the broader process and mandate of Waterfront Toronto, which is first and foremost a land development agency and which has little incentive to think about the deeper connection of those lands and land use activities to the past, present and future of other areas of the city. In future I hope to provide an article about the history of waterfront redevelopment in Toronto, but for now I congratulate the design team for providing this city a compelling public space and interesting, if still to be fully realized, infrastructure solution, and hope we can find ways to go further towards reintegrating our waste streams into the surface environment and experience of urban life.

Michael Cook is available to speak to your organization about infrastructure history, lost creeks, current conditions, and opportunities for change in our management of and communication about urban watersheds, and to work with teams proposing or implementing such change. Get in touch.

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